There is a serious need for an easy to install, inexpensive, simple, trouble free, indicator, mounted on the side of the truck body, which is easily seen from the driver's seat, simply by looking into the rear view mirror. Currently the only way one can check that door, is by stopping the truck, leaving the cab and walking to the back of the truck. This takes time and can be dangerous. We have been in many trucking activities and have had, and witnessed other truckers having serious problems when something is stolen or something accidentally falls from the open rear door of their truck because the driver forgot to close that door. There are many reasons why a driver may accidentally leave the rear roll-up door open. The most common one happens when the driver is in a hurry and his concentration is interrupted just before he is ready to drive off. The driver will then be driving down the road wondering if the door is open or closed. This happens often and worrying about this adds a great deal of stress to the driver, to the point that it can detract the driver from driving safely. We have searched far and wide for a practical indicator to solve this problem with no success.
In defiance of the maxim “keep it simple”, prior art comprises of more and more elaborate and complex mechanisms.
U.S. Pat. No. 4,334,388 (reissued as U.S. Pat. No. 4,562,664) issued to Kambic, shows an interesting door monitor unit, which is capable of indicating a door position. However, this design requires a complex combination of levers, electrical wiring, and switches that would be a maintenance problem if used on a truck with a roll-up rear door.
U.S. Pat. No. 4,835,905 issued to Lasier, et al, discloses a device with complicated parts and actions. This invention requires hydraulics, valves and switches all working together. This requires a difficult installation, which would be cost prohibitive to the truck owners.
U.S. Pat. No. 6,310,548 issued to Stephens, Jr., et al, discloses use of a magnetic field in part of its design. This design also requires electronic sensors and electrical wiring. These components would not be good to use on a truck where vibration and electrical maintenance would be required. This invention is designed for, and would work well in, a home system.
Truck owners are very concerned about corrosion and other maintenance costs. They don't want to add mechanically operated things that cause extra maintenance and they don't like to add electrically operated devices to their trucks because wiring or battery problems are a real headache for them.
No current approach addresses the need for a low maintenance, rear roll-up, truck-door indicator that needs no electrical hookups, no levers, no springs or other mechanical contacts. Our system is very easy to install and is close to maintenance free.
Our invention is made of plastic to make it weather tight and corrosion resistant.
Our invention has only one moving part and that is moved magnetically with no mechanical parts making contact.
Our invention needs no electrical wiring and no batteries to operate.
Our invention has a colorful indicator that is easily seen by the driver, simply by looking into the mirror.
It is therefore an object of the invention to provide a convenient roll-up, rear-door, open-or-closed indicator.
It is another object of the invention to provide a reduction of driver stress.
It is another object of the invention to provide time saved.
It is another object of the invention to provide a means of reducing accidents.
It is another object of the invention to provide an indicator that is clearly visible.
It is another object of the invention to provide an indicator that needs no mechanical or electrical connections.
It is another object of the invention to provide an indicator that has only one moving part, magnetically activated.
It is another object of the invention to provide an indicator that is corrosive-proof and needs no maintenance.
Further objects and advantages are to prevent loss of all or part of the truck's load and provide theft protection. Still further objects and advantages will become apparent from considerations of the ensuing description and drawings.